Many surgical procedures require vessels or other tissues of the human body to be ligated during the surgical process. For example, many surgical procedures require cutting blood vessels (e.g., veins or arteries), and these blood vessels may require ligation to reduce bleeding. In some instances, a surgeon may wish to ligate the vessel temporarily to reduce blood flow to the surgical site during the surgical procedure. In other instances a surgeon may wish to permanently ligate a vessel. Ligation of vessels or other tissues can be performed by closing the vessel with a ligating clip, or by suturing the vessel with surgical thread. The use of surgical thread for ligation requires complex manipulations of the needle and suture material to form the knots required to secure the vessel. Such complex manipulations are time-consuming and difficult to perform, particularly in endoscopic surgical procedures, which are characterized by limited space and visibility. By contrast, ligating clips are relatively easy and quick to apply. Accordingly, the use of ligating clips in endoscopic as well as open surgical procedures has grown dramatically.
Various types of hemostatic and aneurysm clips are used in surgery for ligating blood vessels or other tissues to stop the flow of blood. Such clips have also been used for interrupting or occluding ducts and vessels in particular surgeries such as sterilization procedures. Typically, a clip is applied to the vessel or other tissue by using a dedicated mechanical instrument commonly referred to as a surgical clip applier, ligating clip applier, or hemostatic clip applier. In many procedures, the clip is left in place permanently after application to the tissue. In other cases, the clip must be removed because, for example, only temporary occlusion of a vessel is desired, or the clip has been mistakenly latched to a structure that is not to be ligated. In these latter cases, the clip is removed by using a separate instrument dedicated for that purpose, i.e., a clip removal instrument.
Ligating clips can be classified according to their geometric configuration (e.g., symmetric clips or asymmetric clips), and according to the material from which they are manufactured (e.g., metal clips or polymeric clips). Symmetric clips are generally “U”, “V” or “C” shaped and thus are substantially symmetrical about a central, longitudinal axis extending between the legs of the clip. Symmetric clips are usually constructed from metals such as stainless steel, titanium, tantalum, or alloys thereof. By means of a dedicated clip applier, the metal clip is permanently deformed over the vessel. An example of one such clip is disclosed in U.S. Pat. No. 5,509,920 to Phillips et al. An example of a metallic clip applier is disclosed in U.S. Pat. No. 3,326,216 to Wood, in which a forceps-type applier having conformal jaws is used to grip and maintain alignment of the clip during deformation. Such appliers may additionally dispense a plurality of clips for sequential application, as disclosed for example in U.S. Pat. No. 4,509,518 to McGarry et al.
With the advent of high technology diagnostic techniques using computer tomography (CATSCAN) and magnetic resonance (MRI), metallic clips have been found to interfere with the imaging techniques. To overcome such interference limitations, biocompatible polymers have been increasingly used for surgical clips. Unlike metallic clips, which are usually symmetric, polymeric clips are usually asymmetric in design and hence lack an axis of symmetry. Inasmuch as a plastic clip cannot be permanently deformed for secure closure around a vessel or other tissue, latching mechanisms have been incorporated into the clip design to establish closure conditions and to secure against re-opening of the vessel. For example, polymeric clips are disclosed in U.S. Pat. No. 4,834,096 to Oh et al. and U.S. Pat. No. 5,062,846 to Oh et al., both of which are assigned to the assignee of the present invention. These plastic clips generally comprise a pair of curved legs joined at their proximal ends with an integral hinge or heel. The distal ends of the curved legs include interlocking latching members. For example, the distal end of one leg terminates in a lip or hook structure into which the distal end of the other leg securely fits to lock the clip in place. The distal ends of the clips taught by Oh et al. also include lateral bosses that are engaged by conformal recesses of the jaws of the clip applier. A clip applier specifically designed for asymmetric plastic clips is used to close the clip around the tissue to be ligated, and to latch or lock the clip in the closed condition. In operation, the jaws of this clip applier are actuated into compressing contact with the legs of the clip. This causes the legs to pivot inwardly about the hinge, thereby deflecting the hook of the one leg to allow reception therein of the distal end of the other leg. A clip applier designed for use with asymmetric plastic clips in an open (i.e., non-endoscopic) surgical procedure is disclosed in U.S. Pat. No. 5,100,416 to Oh et al., assigned to the assignee of the present invention.
In addition to compatibility with sophisticated diagnostic techniques, asymmetric clips have other advantages over symmetric clips. For example, because asymmetric clips are formed from polymeric materials, the mouths of asymmetric clips can be opened wider than the mouths of symmetric clips. This allows a surgeon to position the clip about the desired vessel with greater accuracy. In addition, a clip of the type described in above-cited U.S. Pat. Nos. 4,834,096 and 5,062,846 can be repositioned before locking the clip on the vessel or before removing the clip from the vessel, in a process referred to as “approximating” the clip.
As indicated above, instruments employed to install metal and polymeric clips are solely dedicated to the clip applying function, and thus cannot be reversely operated to remove the clip once applied. Accordingly, separate tools have been employed for the sole purpose of reversely deforming and removing clips. In the past, a satisfactory instrument for removing latching polymeric clips had not been available. In past instances where a surgeon desired to remove or relocate the clip, the clip had to be physically severed by appropriate cutting instruments, such as scalpels, scissors and the like. Such removal techniques require substantial time and dexterity to safely remove the clip without adverse consequences to surrounding tissue. Accordingly, a need arose for developing a surgical instrument for removing plastic latching clips in a manner that released the clip from a latched condition in a single piece without destruction of the clip and damage to surrounding tissue. In the case of open surgery, these problems have been addressed by an open, forceps-type clip removal instrument disclosed in U.S. Pat. No. 6,391,035 to Appleby et al., assigned to the assignee of the present invention. The need remains, however, for a polymeric clip removing instrument having an improved jaw design to enable better handling of and control over such clips, as well as for a clip removing instrument suitable for use in endoscopic-type surgical procedures, particularly an instrument that successfully addresses the problems attending the use of asymmetric clips.
As a general matter, laparoscopic, endoscopic, and other minimally invasive surgical techniques enable surgeons to perform complex procedures through relatively small entry points, or surgical ports, in the body. The term “laparoscopic” refers to surgical procedures performed on the interior of the abdomen, while the term “endoscopic” refers more generally to procedures performed in any portion of the body. Endoscopic surgery involves the use of an endoscope, which is an instrument permitting the visual inspection and magnification of a body cavity. The endoscope is inserted into a body cavity through a cannula extending through a hole or port in the soft tissue protecting the body cavity. The port is typically made with a trocar, which includes a cutting instrument slidably and removably disposed within a trocar cannula. After forming the port, the cutting instrument can be withdrawn from the trocar cannula. A surgeon can then perform diagnostic and/or therapeutic procedures at the surgical site with the aid of specialized medical instruments adapted to fit through the trocar cannula and additional trocar cannulas providing openings into the desired body cavity.
Some known advantages of minimally invasive surgical techniques include reduced trauma to the patient, reduced likelihood of infection at the surgical site, and lower overall medical costs. Accordingly, minimally invasive surgical techniques are being applied to an increasingly wider array of medical procedures.
Surgical clip appliers and removers adapted for endoscopic surgical techniques typically include a shaft that is inserted through an endoscopic cannula to access a surgical site in a body cavity and a jaw assembly disposed at the distal end of the shaft for manipulating a surgical clip at the surgical site. The basic operations of endoscopic clip appliers and removers are as indicated above. The clip applier is used to position the clip over the desired vessel and its jaws are actuated, typically using an actuating mechanism disposed in the handle of the device, to close the clip about the vessel. In certain cases such as those previously mentioned, the clip remover can be used to unlatch the clip.
As endoscopic techniques have been developed, certain inadequacies in the available surgical equipment have become apparent. For example, the jaws of the removing instrument, which are typically used to disengage the clip from the vessel, may exert unequal pressure on the clip, resulting in a “scissoring” effect and damage to the vessel. In addition, the jaws may impart excessive force on the clip and consequently crush the clip, thereby creating a risk that pieces of the clip are not removed from the body cavity. In prior art devices, the force applied to the clip has been difficult to control by the surgeon using the clip removal instrument. In other instances, the clip may not be properly oriented when it is placed within the jaws, or may slip out of alignment or even be ejected from the jaws during use of the removal instrument. This can result in the loss and/or crushing of the clip or pieces thereof, damage to tissue, or otherwise unsuccessful use of the removal instrument.
Moreover, existing clip removal instruments have been designed primarily for manipulating symmetric clips, and therefore are not well suited to satisfy design issues unique to asymmetric clips. For example, when symmetric clips are closed on a vessel, the opposing legs of the clip apply substantially even pressure to the opposing sides of the vessel. By contrast, the opposing legs of an asymmetric clip can apply varying pressure to opposing sides of a vessel when the asymmetric clip is closed. Thus, ideally a clip removal instrument should be designed to account for the asymmetry of the clip, so as to avoid the above-mentioned unequal pressure on the clip and resulting damage to the vessel. Further, lockable asymmetric clips generally function best when force is applied at or near the distal ends of the clip legs. Still further, asymmetric clips usually need to be placed under compression to be unlatched. Conventional clip removal instruments designed for symmetric clips may not provide the ability to adequately compress or approximate a clip.
As an additional problem, while clip removers of the prior art are capable of unlatching the clip, once the clip has been unlatched, the same instruments are not additionally capable of actually removing the clip from the surgical site and subsequently extracting the clip from the body cavity through the surgical port. An additional clip-grasping instrument has conventionally been required for this purpose. It therefore would be advantageous to provide a clip removal instrument that is capable of both unlatching the clip as well as grasping the clip for extraction from the surgical site.
In view of the foregoing discussion, a need is acknowledged by persons skilled in the art to provide an endoscopic clip removing apparatus that enables improved control over manipulation of a clip, especially a surgical clip and particularly one of asymmetric design. A further need is acknowledged to provide an endoscopic clip removing apparatus that, in use, prevents the clip from being crushed, especially polymeric clips that are more prone to breaking in comparison to metal clips, and prevents damage to tissue. A still further need is acknowledged to provide an endoscopic clip removing apparatus that is capable of not only unlatching a clip but also thereafter removing the clip from the surgical site.